The present invention generally relates to a bearing mount, and in particular to a composite resilient mount for rolling element bearings.
Rotating machinery is subject to vibration during operation at various speeds. Such vibration may be due to: (1) approaching and/or traversing rotor critical speeds or (2) misalignment between the rotor itself and one or more bearings for the rotor. Machinery operated at high rotational speeds, for example, at speeds greater than 30,000 rpm, is particularly prone to both types of vibration. Vibration of the rotor and other rotating parts increases the radial load on the bearings and may lead to premature failure of the bearings.
Attempts to decrease vibrations in high speed rotors have included the use of resilient mounts arranged external to the outer raceway of the bearing. As an example, U.S. Pat. No. 5,564,903 to Eccles et al. discloses a ram air turbine power system, including a bearing mount ring disposed between a thrust liner and a bearing carrier, wherein the mount ring includes a first set of radially outwardly extending pads, a second set of radially inwardly extending pads, and flexible beams between the radially outwardly extending pads radially inwardly extending pads. The mount ring of Eccles et al. may further include axial pads extending axially at opposite ends of the mount ring, wherein the axial pads respectively engage thrust shoulders on the housing and on the bearing race.
U.S. Pat. No. 5,044,784 to Lisowsky discloses a bearing isolator for absorbing vibration and acoustic energy, wherein the bearing isolator comprises an inner spoked metal ring for registration with the outer raceway, an outer spoked metal ring for attachment to a mounting structure, and an annular member disposed between the inner metal ring and the outer metal ring. The annular member may comprise a resinous material, such as polyimide or epoxy, and a minor fractional fill of graphite, glass particles, or glass fibers.
U.S. Pat. No. 6,540,407 to Van Dine et al. discloses a rolling element bearing arrangement comprising an inner race facing in one lateral direction, and an outer race facing in a second, opposite lateral direction. A vibration inhibiting outer ring member, which may comprise a heavy metal or a resilient material, is disposed against the outer surface of the outer race. The vibration inhibiting outer ring member may be retained against the outer race by a composite wrap.
Although prior art mounts may decrease vibration of rotating machinery, nevertheless, vibration remains a potential problem at certain speeds. For example, the vibration inhibiting outer ring member of the '407, even when combined with the composite wrap, is unlikely to provide sufficient damping or stiffness to a bearing to prevent vibration of a high speed rotor. In addition, the heavy metal construction of the vibration inhibiting outer ring member adds excessive weight to the machinery, which is of particular concern in aerospace applications.
As can be seen, there is a need for a single-component, resilient mount for rolling element bearings that provides radial damping to prevent vibration of high speed rotating machinery. There is a further need for a resilient mount that is light in weight, and which will not damage bearing housings or other components of rotating machinery.